The effects of viscoelastic parameters on residual stress development in a zirconia/glass bilayer dental ceramic.

OBJECTIVES: The aim of this study was to test the hypothesis that the residual stresses in a zirconia-based bilayer dental composite system can be tailored through heat treatment above and below the glass transition temperature of glass veneers. METHODS: Ceramic bilayer disc specimens were prepared from a zirconia core and a glass veneer. Each bilayer ceramic group was heat treated 40 degrees C below, 20 degrees C and 40 degrees C above and at the glass transition temperature of the glass veneer, and cooled using a fast or a slow cooling rate. Specimens were tested for flexure strength using a biaxial bending fixture. Residual stresses were calculated using a fracture mechanics approach. RESULTS: Heat treatments produced significant differences (p < or =0.05) between the mean flexural strengths of the heat treatment groups when the specimens were cooled using a fast cooling rate. However, there was not a significant difference (p >0.05) between the mean flexural strengths of the heat treatment groups when a slow cooling rate was used. Fractures initiated from the veneer surfaces of the specimens. SIGNIFICANCE: Heat treatment above and below the glass transition temperature of the veneer layer, and the cooling rate have a significant effect on the flexural strength of the bilayer ceramic laminates. The existence of residual compressive stress is the most likely reason for the observed strength increases. Residual stresses can be modified using the elastic-viscoelastic relaxation behavior of a glass veneer.     

Chlorhexidine's effect on sealing ability of composite restorations following Er:YAG laser cavity preparation

AIM: The aim of this study was to evaluate the influence of chlorhexidine on microleakage of composite restorations in class V cavities prepared with a carbide bur (CB) and a erbium:yttrium-aluminum-garnet (Er:YAG) laser. METHODS AND MATERIALS: Cavity preparations were created on the buccal surfaces of 48 bovine incisors using different methods then equally dividing them into four groups. Groups I and II were prepared with a #56 CB in a high speed handpiece while Groups III and IV were prepared with a Er:YAG laser at 350m J/4Hz on enamel and at 80.24 J/cm2 on dentin. The cavity preparations were rinsed with 2% chlorhexidine solution before the application of Clearfill SE Bond system and placement of a Z100 composite resin restoration. After 24 hours, the teeth were polished, thermocycled, and sealed with cosmetic varnish. The samples were then immersed in 2% methylene blue for four hours and sectioned in the buccolingual direction to determine the degree of microleakage. RESULTS: After statistical analysis (Kruskal-Wallis, p<0.05), no significant differences were verified among the tested groups and between the evaluated cervical or incisal margins of the restoration. CONCLUSION: The use of the chlorhexidine did not interfere with the adhesion process regardless of whether a CB or the Er:YAG laser were used to prepare class V cavities when restored with the tested self-etching adhesive system.     

Core curricula for postdoctoral dental students: recent problems, potential solutions, and a model for the future

Development of common core curricula for the graduate advanced education/specialty programs in dental schools presents significant challenges. Similarities in graduate education accreditation standards justify such an approach, yet a core curriculum is difficult to achieve for a variety of reasons including scheduling constraints and the capacity of a common, single pathway curriculum to address the specific educational needs of postgraduate students in different disciplines. Additionally, many dental schools are experiencing severe shortages of qualified faculty to provide graduate program instruction. There are no previous reports regarding graduate core curricula and the definition/delivery of such core curricula in advanced education programs in dentistry although there are several reports in the medical literature that support the educational value of a unified core curriculum implemented in a modular format. Graduate curricula are typically designed to provide residents with advanced education/training beyond what is acquired during their predoctoral dental school experience. Advanced education programs must emphasize knowledge and skills that are discipline-specific; however, there is a large amount of common foundational material within the early phases of these programs. Dental schools have attempted to identify and present this common material within the context of an organized shared set of courses/seminars where residents from each advanced education program are scheduled simultaneously. However, there have been problems with the implementation of a shared core curricula including the following: 1) dissimilar educational backgrounds/abilities among residents; 2) relevance of material to all residents; 3) lack of central management; 4) scheduling conflicts; and 5) lack of adequate and consistent program evaluation. In an attempt to resolve these problems, a new comprehensive graduate core curriculum was implemented at the Marquette University School of Dentistry in 2000. This core curriculum was designed to 1) be user-friendly; 2) allow flexibility; 3) meet specific programmatic/accreditation needs for each advanced education program; and 4) provide assessment tools for continuous resident feedback and curriculum improvement. Assessment data obtained from residents, faculty, and program directors indicate that this approach has been successful and has transformed graduate education at Marquette. Thus, this model may prove useful for other institutions seeking to refine or develop graduate core curricula.     

Proposal for a 'surgical checklist' for ambulatory oral surgery

The authors propose a new checklist model adapted for ambulatory oral surgery procedures based on the ‘surgical checklist’ proposed by the WHO. The proposed document contains 18 items divided into two sets: those that must be verified before beginning surgery and those that must be verified after its completion, but prior to the patient's departure from the site where the surgery is performed. A checklist is an easy-to-use tool that requires little time but provides order, logic and systematization taking into account certain basic concepts to increase the level of patient safety. The authors think that the result is a checklist that is easy to complete and ensures that key patient safety-related matters are dealt with in this field of surgery.     

Applicability of an Albanian version of the OIDP in an adolescent population

International Journal of Paediatric Dentistry 2011; 21: 289–298 Background. The impact of oral conditions on quality of life of adolescents has not been thoroughly investigated. Aim. The purpose of this study was to assess the reliability and validity of an Albanian version of the oral impact of daily performance (OIDP) questionnaire. Design. A total of 493 adolescents attending secondary public schools in Albania attended clinical examination and completed a questionnaire that included an Albanian version of the OIDP inventory. The psychometric properties of the OIDP were evaluated in terms of reliability and validity. Results. The validity and reliability of the Albanian version of OIDP were good. Cohen’s Kappa ranged from 0.72 to 0.79. In terms of internal consistency, Cronbach’s alpha was 0.77. Construct and criterion validity were demonstrated in that the OIDP frequency scores were statistically significant with global measures of self‐rated and self‐perceived oral health status variables and some of the clinical variables used in this study. A total 60.9% of participants reported having at least one oral impact. The most prevalent impact was difficulty in smiling, whereas difficulty in speaking was less prevalent impact. Conclusion. The Albanian version of OIDP seems to be a reliable and valid scale for use in an urban adolescent population.     

The effect of carbamide peroxide bleaching agents on the microhardness of dental ceramics

This study examined the effect of 10% and 16% carbamide peroxide bleaching agents on the surface microhardness of micro-particulate feldspathic ceramics (VM7 and VM13, Vita Zahnfabrik). Forty specimens (8-mm diameter, 2-mm thickness) were divided into four groups (n=10): GI-VM7 + 10% Whiteness, G2-VM7 + 16% Whiteness, G3-VM13 + 10% and G4-VM13 + 16% Whiteness. The home-use bleaching agents were applied for 8 hours on 15 days, and the specimens were stored in distilled water at 37 degrees C. The Vickers hardness number (HV) was determined for each specimen. Data were analyzed by the Wilcoxon and Mann-Whitney tests (p < 0.05). The microhardness values before exposure were: g1-433 (57); g2-486 (22); g3-509 (28); g4-518 (24), and after exposure: G1-349 (32); G2-496 (95); G3-519 (38); G4-502 (81). G2 exhibited a higher and significant difference than GI in VM7 groups, and the effect of bleaching concentration was shown to be significant by the Mann-Whitney test. And for VM13, both the Wilcoxon and Mann-Whitney tests showed no significant differences. When using 10% carbamide peroxide, the microhardness of VM7 ceramic was affected, and there were no effect on the microhardness between VM7 and VM13 ceramics when 16% carbamide peroxide was used.     

Dental treatment improves self-rated oral health in homeless veterans--a brief communication

OBJECTIVE: The aim of this study was to assess homeless veterans' perception of their oral health and the impact that oral disease and treatment have on self-assessed quality of life. METHODS: Outcomes included measures of general and oral-specific quality of life and functional status. Single-item self-report of oral health and the General Oral Health Assessment Index were assessed at baseline and after treatment. RESULTS: One hundred and twelve veterans completed the baseline questionnaire, and 48 completed the follow-up. Veterans who were eligible for ongoing dental care had improved General Oral Health Assessment scores, while patients who received only emergency dental care saw a decreased score (2.46 versus -2.12). General Oral Health Assessment improvement was significantly related to fewer teeth at baseline (18 versus 23), a lower baseline General Oral Health Assessment (23.6 versus 28.1), having a denture visit (22 versus 35 percent), and improvement in self-reported oral health (25 versus 42 percent). CONCLUSION: There was significant improvement in homeless veterans'perceived oral health after receiving dental care.